This invention relates to polycarbonates containing additives which increase the thermal stability thereof.
Polycarbonates derived from reactions of dihydroxyorganic compounds, particularly the dihydric phenols, and carbonic acid derivatives such as phosgene have found extensive commercial application because of their excellent physical properties. These thermoplastic polymers appear to be particularly suitable for the manufacture of molded parts wherein impact strength, rigidity, toughness, heat resistance and excellent electrical properties are required.
It is found, however, that the polycarbonates exhibit poor thermal stability. Heretofore in order to improve thermal stability of the polycarbonate, cyclic phosphites have been added to the polycarbonate. Unfortunately, such phosphites deleteriously affect the hydrolytic stability of the polycarbonate.
In view of the deficiencies of many of the conventional polycarbonate compositions, it is highly desirable to provide a polycarbonate composition having improved thermal stability without adversely affecting other properties of the polycarbonate such as hydrolytic stability, tensile and impact strength, and molecular weight.